/* Copyright (C) 2006-2007  Egon Willighagen <egonw@users.sf.net>
 *
 * Contact: cdk-devel@lists.sourceforge.net
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 */

namespace NCDK
{
    /// <summary>
    /// Class representing a ring structure in a molecule.
    /// A ring is a linear sequence of
    /// N atoms interconnected to each other by covalent bonds,
    /// such that atom i (1 &lt; i &lt; N) is bonded to
    /// atom i-1 and atom i+1 and atom 1 is bonded to atom N and atom 2.
    /// </summary>
    // @cdk.module  interfaces
    // @cdk.keyword ring
    public interface IRing
        : IAtomContainer
    {
        /// <summary>
        /// The number of atoms/bonds in this ring.
        /// </summary>
        int RingSize { get; }

        /// <summary>
        /// Returns the next bond in order, relative to a given bond and atom.
        /// Example: Let the ring be composed of 0-1, 1-2, 2-3 and 3-0.
        /// A request GetNextBond(1-2, 2) will return Bond 2-3.
        /// </summary>
        /// <param name="bond">A bond for which an atom from a consecutive bond is sought</param>
        /// <param name="atom">A atom from the bond above to assign a search direction</param>
        /// <returns>The next bond in the order given by the above assignment</returns>
        IBond GetNextBond(IBond bond, IAtom atom);

        /// <summary>
        /// The sum of all bond orders in the ring.
        /// </summary>
        int GetBondOrderSum();
    }
}
